Remote positioning and indicating system



May 24, 1949.

w. P. LEAR 2,471,220

REMOTE POSITIONING AND INDICATING SYSTEM Filed Jan. ll, 1944 ssheets-'sheet 1 ATTORNEY May 24, 1949. n w P, LEAR 2,471,220

REMOTE POSITIONING AND INDICATING SYSTEM Filed Jan. 411, 1944 3sheets-Sheet 2 JNVENTOR. /4///4/1/ P. EAA

WAR

ATTORNEY May 24, 1949. w. P; LEAR 2,471,220

REMOTE POSITIONING AND INDICATING SYSTEM s sheets-sheet s Filed Jan. ll,1944 ATTO RNEY Patented May 24, 1949 UNITED STATES PATENT OFFICE REMOTE.POSITIONING AND INDICATING .SYSTEM 'WilliamR-Lear, North Hollywood,Calif., assigner, by mesne assignments, to Lear, Incorporated, GrandRapidsfiMieh., -a corporation of Illinois ,Application January 11, 1944,Serial No. 517,831

lIt is necessary that such accessories -be rmoved to and retained vincertaindesignated `positions at the control of the pilot. For thispurpose, it is desirable to provide, adjacent thepilots-compartment, andpreferably on the instrument panel, simple reliable remote control meansby which the position of theaccessoriesmay be controlled and theirposition at all times indicated tothe pilot.

It is, among the objects of this ,inventionito provide a novel remotepositioning and indicating unit `for lpredetermining or presetting 'thedegree of desired motion to ,take ,place` in a movable member; toprovide such a -unit Vhaving a visual position indicator; to providesuch a unit vacting asa manually operated offand on Switch for thecontrol oi the power means fory anlactuator operating themovablemember;,to provide such a unit which is compact, Yof ysmall dimen- 9 sions andhas operating parts arranged as acomplete vunit which maybe readilyassembled and disassembled froman instrumentpanel; toprovide such aunitincluding a manuallyioperated position selector and a positionindicatoroperated by means synchronously connectedito` driving meansvfor an actuator .operating the 'movable member; tovprovide asystemincludingsuch unit and dynamic braking means for ',substantiallyinstantaneously-stopping motion ofthe position indicator and themovable-member .When

the latter have reached the desired preselected position; and to providea remote positioning and indicating system embodying Vsuchnovel 4remotepositioning and indicating unit.

These and otherobjects, advantages a-ndzfeatures of theinvention willbeapparentffromthe following description and accompanyingdrawings. Inthe drawings:

Fig. 1 is a front viewof .a remote positioning tand indicating unitforming partof the invenion.

Fig. 2 is aside `elevation view of the unit illustrated in Fig. 1.

Fig. 3 is an elevational .view on-an venlarged CII scale and partly insection of the unit illustrated 'in Figs. l and 2.

tally, of theposition selecting andindicatingtunit.

Fig. 9 is a schematic View cfa Completefposition selecting andindicating-system according to the present invention.

Fig. 10 is a schematic wiring diagram'illustrating circuit connectionsfor the system illustrated in Fig. 9.

According to the present-invention, a position selecting and indicatingunit is provided including a manually operated position indicator. fSuch position selector and indicator is operated, through reductiongearing, byia controlfknob mounted on the front `of the mechanism, Thecontrol knob also operates a switchmounting plate which is operativelyassociated Wthacam in such a manner that, uponmovement of the plate, theswitch mounted thereon iS closedin one direction or the otherto,energize'a-motor operating an actuator connectedto the-member to bepositioned. Upon the closing of the circuit thereto, the actuator motoroperates tomovethe movable member to the indicated position..Simultaneously, meansforming part of the unit ,is operated insynchronism with the actuator motor, to move the aforementioned cam anda .Dosition indicator into coincidence lwitlithe position selector. Whensuch coincidence is, achieved, the cam operates to open the switchen.the mounting plate, deenergizingrthe actuator motor and, preferably,effecting a dynamic brakingoircuit therefor.

Referring more particularlyto Figs. l through 8 of the drawings, theinvention includes apasition selecting and indicating unit l5lcomprising a housing I6 enclosing the selectingand ,indieatingmechanism to which is secured means 20 arranged to operate the positionindicator.35 lin synchronism with an actuator driven positionablemember. In the present instance, the means 2G comprises a direct currentmotor drive unit provided with a mounting plate i1 having a flange I8secured to a ange 2| of housing |6'by detachable means such as screws22. The se- 3 lecting and indicating unit includes an operating knob 3Uwhich is adapted to move a position selector or pointer 25 incooperation with indicia 23 which may be provided on the face plate 24of the mechanism.

Through an arrangement to be described hereinafter, operation ofselector knob 3@ eiects energization of an electric motor driving aremote actuator for a movable member. Drive unit Eil is electricallyconnected to the remote actuator for the movable member in such a nanner that it will operate position indicator 35 in synchronism with themovable member. When position indicator 35 is brought into coincidencewith position selector 25, the electric motor for the movable memberactuator is automatically deenergized, as will be described.

In the present instance, drive unit 2li includes an electric motor iswhich is electrically connected to the motor for the actuator in such amanner as to operate in synchronism therewith. For example, motor lliand the actuator motor may be synchronous alternating current motorsoperated from the san-ie source or alternating current. However, as isoften the case on aircraft, motor I9 and the actuator motor may bedirect current motors as these will oneate from the storage batteriesnormally ce ried aboard the aircraft and have a high tial torque value.synchronizing means must be provided for such direct current motors.Also Where desirable, a flexible shaft may be used of motor unit 2li tocouple indicator 35 to the remote actuator, similarly to the arrangementshown in my Patent No. 2,355,381, issued August lilac for Preselectioncontrol mechanism assigned to the same assignee.

For a general understanding of the operation of the position selectingand. indicating mechn anisrn, reference may be had to the exploded View,Fig. 8. Control knob at is connected through a safety or slip clutch 2lito reduction gearing schematically illustrated at i'i and 25. Clutch 25is provided to insure that position selector 25 will `be moved atsubstantially' the same rate of movement as the actuator drivenpositionable member. Thus, if the operator, such as a pilot, rotatesknob Si) at rate in excess of the normal rate of movement for which thepositionable member is designed, slip clutch will disengage and nomovement w be transn mtted from knob 3l? to position selector lo untilsuch time as clutch 2S again becomes engaged, namely after substantiallya complete revolution of knob 3s. Member 2S of the reduction gearing isconnected to the position selector and wise to a switch mounting plateon which mounted a single-pole double-throw switch Reduction gearing 2l,2li is provided to move position selector 25 at a rate substantiallyequal to a rate of movement of the positional-cle member. The reductionratio of gear is Selected after consideration of the operating speed orthe positionable member with respect to the possible operating speed ofcontrol knob 39. This affords the pilot a natural feel he desires forcontrolling remote members on the airplane. In the present instance, areduction ratio of substantially twenty to one has been found to besatisfactory. Canin-witch 32 is adapted to be operated by a cammechanically connected with position indicator Cam 'd selector 2lithrough slip clutch 2o and reduction gearing 2l, 23, is moved at areduced rate to the indicated position. At the same time, mounting plate3i is moved in one direction or the other so that cam 33 will close oneor the other of the contacts of switch 32.

ln a manner to be described more fully hereinafter, cam 33 closes thecontacts of switch 32 to complete a circuit for the actuator motor foroperation thereof in a direction to position the movable member inaccordance with the direction of movement of position selector im.Operation of the actuator motor effects movement of drive unit 2li in adirection to bring position indicator 35 into coincidence with positionselector 25. Drive unit 2U also operates cam in synchronism withposition indicator t5. When coincidence between indicator 35 andselector 25 is achieved, cam 33 will have moved switch to a neutralposition deenergizing the actuator motor. In a preferred embodiment orthe invention, such deenergization activates a dynamic braking circuitfor the actuator motor as will be described. ln the present instance,switch also controls energization of motor l@ of drive unit 2t foroperation in synchronism with the actuator motor.

Referring more particularly to 1Figs. 3 through 7 showing details or theselector unit, knob comprises a disk portion il! and a rim portion i2which forms a housing enclosing the reduction gearing for the indicatingmechanism. A gasket il is interposed between rim and selector E. Knob 3Sis rotatably mounted on a bushing i3 disposed on a shaft lit. An annularmember l5 is secured to disk portion fil by pins i6 and is formed with ashallow groove il (Fig. 3) around its inner periphery. Adjacent one partof its periphery, member t5, as may be seen more clearly in Fig. l, isformed with an aperture l intersecting groove ill.

Clutch 25 is disposed internally of member l5 and likewise mounted onbushing at, and has a recess 5l in which is disposed a spring 52. Spring52 urges a ball 53 into engagement with groove lll. Normally, -ball 53engages aperture 48 to form a slip connection between knob 3d and clutch2t. A plurality of pins 55s extend between clutch 26 and a backing plateand sleeves 56 on the pins maintain clutch il@ and plate 55 properlyspaced. As explained heretofore, the function of clutch 25 is to insuremovement of selector 25 at a rate not greater than the normal rate ofmovement of the member to be positioned.

Shaft lil is formed as an integral extension of cam 33 and positionindicator is secured to the outer end of shaft by a screw di. A springwasher 53 is interposed between indica tor 35 and disk portion il ofknob 3i?. Adjacent its inner end, shaft l is formed with recess lill,and cam 33 is formed with a shallow groove El having parallel sides, asshown more clearly in Fig. 6. Recess Sil receives the reduced end lillof a shaft Hi8, forming part of unit 2t, and groove El receives a1iattened portion i ii of shaft M58. This arrangement establishes adetachable driving connection between drive unit 2li and selector andindicator unit l5.

A gear 52, formed with an elongated hub is mounted on shaft lli abuttingbushing fli. The inner end of hub E3 is splined at till and engages aninternally splined bushing 35 secured by rivets 56 to switch mountingplate 3l. Housing lli is formed with a tubular extension Sl larrimagesurrounding hub 83 and having a-splinedinner Aendf'68 engaging-agear"19. 4Grear'ii'is therefore 'fixed with respect'to housing I8. A splinedsleeve 1| surrounds extension "fiT-a-ndextends through an aperture inplate-55 on the opposite side of which its teeth -engage'internal teeth12 -on position selector25. A gear -13 has a splined hub engaging thesplinedv inner end of sieeve1| and is rotatable with vselector 25.

Three pinions 14, Y1-5 and'16 are disposed in adjacent relationand-xed-to sleeve 156 on one-oi the pins 54. Pinions A14, and 18 ymesh,respectively, with gear '62, -gear 19 and gear i It wiugbe noted thatgears a2 and ia are Substantially equal in external diameter vwhereasgear 10 issomewhatsmallerlin-diameter. Gears t2 and 13`are, in operativeeffect, asingle gear corresponding to gear r28 of Fig.4 8.yLikewise,.pinions '-14 and 18 yare -substantially equal in diameterand, in operative effect, ycomprise a single pinion, whereas pinion'15is somewhat larger in diameter. Accordingly, rotation of the pinionunit, which corresponds to pinion 21 of Fig. 8, will eiect differentialrotation -of gears 82 and 13 with respect to gear 18. Thefratio ofmovement will be proportionai to the number of teeth difference betweengea-r 1 Band gears 82 and 13. Thus, selector 25 willbe moved at agreatly reduced rate with respect'to knob 30. Such gear reductionachieves fineness of control of position selector 25.

As shown more clearlyin Fig. 6, switch mounting plate 3| isprovided-with discontinuous slip rings 11 and '18. AAdjacent oneend ofthe slip rings, 'a movabie switch arm '88 is pivoted to plate v3| andnormally urged in an inward direction by a spring 8|. lSwitch varm l89is formed with a radially Ainwardly directed projection 82 adapted tocooperate ywith cam 83. The outer end 83 of arm 89 engages a springcontact 84 i forming part ofswitoh '3-2. Spring contact 84 is mounted ona block 85 secured to plate 3| adjacent the opposite end of rings 11 and18. Contact is adapted to engage either one of a pair of spaced contacts-88 and 81, and the arrangement is such that contact 84 is normallyurged toward contact `$51. Contacts 88, 81 are connected to slip rings11, 18, as diagrammatically indicated and brushes 19, 19 connect theslip rings in the motor control circuit.

Cam 33 isiorined with semi-circular surfaces 9G and 9| which are joinedby diametrically opposite sloping or neutral-position surfaces 92 and 93. When the' projection 82 on switch arm 8|) engages either cam surface92 or v`v93, contact- 84 is held in a-neutral position between contacts86 and 91. YIf lplate 3| is moved relative to cam y33, projection 82will engage either of the semicircular s uraces99 or 9| to causeengagement between contact 34 andfcontact 88 or 81 respeci on plate l1.An outer plate 98 is secured to posts |99 mounted in piate I1. The motorpinion |0| meshes with a gear |82 secured to a worm |83. Gear |512 andworm l|03 are mounted in suitable bearings inplates 1 and 9 3. Wornrlengages Aa worm gear |04 secured on a worm |05. Gear v-|`04 and worm |95arelikewisemounted in suitable'bearingsisecured'to plates "l1 and98.Worm -I 05 meshes with a-second-fworrn gearll 06 mounted 'in -abearing|81 secured-toiplate-"98, rThe shaft |88ofworm gear `|l|i| isYformed-witha-reduced -outer end portion ||0 engaging-recess 60 in shaftselector VA25at the desired pointwithrespect to indicia 243.vWhen--theoperator :turns knob-30, clutch 28 is driven through rball\`53. However, ifknob '38 is-rotatedat'a rate exceedingthe actual frateor` movementV ofy the-.aotuator. positioned movable member,thevcl'utch-.will slip. Thereby,

the-positional .memberfiwmoved at a rate substantially the vsan-reas fitnormally would be if manually operated lbylthe vpilot through direct-n'iechanical-fmeans. Movement-of vknob 30 :thus

gives the pilot fthe samenatural feel hewould obtain if he-were manuallyoperating the positionable member.

Rotation of clutchmember .26 revolves pinions 11i, 15 and 18abouttheperipheries of gears 82, and i3. For operative purposes, pinions14 and 18 may be considered :as .fone pinion and gears S2 and '-13 asazsingle gear. vDue :to the difference in the diameters-and Vthenumberof teeth o gears 82 and 13-.with respect to gear lis', relativerotation .of .gear J.|.'|.with respect to gears 62 and .13 'will.-beobtained. VGear 19 is fixed. Therefore, aspinions14, 1'5 and 16rotate around the gears, gears-:162;and13- will be rotated with respectto gear :10.byfan .amount proportional to the number .offlteethdiffer-ence between gears-82 `and413 andqgear 10. `:In turn, .these willcause a Vcorresponding displacement of selector 25 Iand switch -mountingplate `3| in unison. Stops iii and .=||2 '(Fig ll) limit movement ofselector :25 ineither direction.

iispiacenient of plate 33| .causes switch arm 89 to be moved withrespectftocam 33, out of engagement with -neutralicam-portion v92 or 93,and to engage veither :surface 190 or surface 9| .'thereoi. This engagesmovable switch contact 94 with one of the xed contacts 8,8 or 91 toeffect energiaation ofv-thefactuator `motor in a direction to rmove theipositionable :member in accordance-with Ithe. directionof movement ofselector 25. The vactuator;motor yis energized overcircuits,describedinconnection with Figs. 9 and 10. Drive unitEnoperating i n,synchronism with the actuator for thepositionablemember, moves cam 33 and indicator 35; in synchronism with the movementof the movable member and in a direction to restoreeoincidence betweenselector 25 and indicator 35. .When -the lselector and indicator are.brought into .-Coincidence, projecion 82 of yswitch arm. 80 yengageseither neutral portion 92 or 93 of cam 33, thus movingmovable switchcontact 84 to 1its neutral position and realring the energiaingcircuitfor the actuator motor. Inthe presentinstance, switch .32 also controlsthe energizing circut-for-rnotor I9 which operates in synchronism withthe actuator motor.

The use of .the preselectormechanism of the present inventioninaremotepositioning and indicating system willnow `be described moreparticularly with reference to Figs. 9 and 10. In Fig. 9, preselectorunit |5 is shownas arranged to vcontrol the position of ajnovable memberA|.|'5 vwhich may be, for instance, auflaporanintercooler shutter of anairplane. "Flap |15 is pro..

v"vided with a crank arm connected through link Ill to the extensiblemember Il of a mechanical actuator, which may be of the type describedand claimed in my copending application Serial No. 483,515, led April17, 1943, now Patent 2,469,269, issued May 3, 1949, entitled Unitarymechanical actuator device. In the present instance, the electromagneticclutch and brake unit of said copending application is omitted, and theactuator motor drives a screwjack |'2l directly through the medium ofgearing contained in a housing |22. Braking is provided by a dynamicbraking arrangement.

A source of electric power, in the present instance direct current, isindicated at |23 and is connected to switch 32 by leads |24. Indicatorl5 is connected to control box |25 by leads |25, and motor le isconnected thereto by leads l2?. Other leads |28 -connect control box |25to motor lim. Drive unit 2t and motor i2!) are operated in synchronism.In the present instance, drive unit Bil includes direct current motori9, motor |243 likewise ,being a direct current type. In order thatdirect current motors i9 and |253 will operate in synchronism, eachmotor is provided with a set o1 slip rings It@ and Vil, respectively.Rings |33 or i3! are connected to electrically spaced points of thearmature windings of the motors. Circuit connections |32 interconnectthe slip rings |35 and |3| through brushes |33 and |34, respectively.

As will be understood by those skilled in the art, upon a relativedisplacement or" the armatures of motors |39 and |3l, circulatingcurrents will be introduced into leads |32 to maintain synchronousrotation of the D. C. motors. Motor i229 is a relatively large motorhaving sufficient power to operate actuator |2|, whereas motor i@ is arelatively tiny motor of suiiicient power to operate indicator 35 andcam t3 through reduction gearing 35. Accordingly, the synchronizingaction is substantially all eiected on relatively small motor i9, therelatively small circulating currents having a correspondingly greatlyincreased eiect upon motor I9 as compared to their effect upon the muchlarger motor |2. Thereby, motor l'ii is effectively tied to motor |26for operation in synchronism therewith.

In Fig. 9, the system is shown at an intermediate point of a controlcycle. Position selector 25 has been moved counter-clockwise to thepoint 4. This has eected an energization of motors i9 and |29. Thesemotors operate in synchronism, as previously described. Motor itil,through screwjack |2l, moves lap H5. in synchronism therewith, motor i9moves cam 33 and position indicator 35 toward coincidence with positionselector 25. When member ||5 has been moved to the position of selector25, indicator 35 will coincide with selector 25 and both motors will bedeenergized through the action of cam 33 on the switch 32.

An electric circuit arrangement for accomplishing the foregoing using adirect current motor drive as used in many aircraft installations isindicated schematically in Fig. l0. Direct current motors operate oilstorage batteries and have high initial torque values. As shown inFigure 10, movable contact 85 of switch 32 is adapted to connect eithercontact St or 8l to ground. Contact 86 is connected to one terminal of arelay |36, and contact 8l is connected to one terminal of relay |31. Theopposite terminals of relays |36 and |31 are connected in parallel witheach other and in series with one terminal of a slow release or delayedaction type of relay |38. The opposite terminal of relay |38 isconnected to the positive side of source |23. Relays |36 and |31 areprovided with contact arms |40 and lili, respectively, which areconnected to opposite terminals of armatures |42 and |43 of motors I9and respectively. It will be noted that motor armatures |42 and |43 areconnected in parallel with each other across their brushes. Normally,arms Idil and Ml engage back contacts IM and |45 of relays itt and |37,respectively, which are connected to positive terminal |23. Frontcontacts |555 and ll or relays |35 and |31 are connected to ground.Fields |68 and |49 of motors i9 and mi, respectively, are likewiseconnected in parallel. One side of the iields is connected to ground andthe other side is connected to a normally open contact arm |56 of relay|38. Front contact |5i of relay |33 is connected to the positiveterminal of the source |23.

Should selector knob 3G be moved in such direction as to cause switcharm im to engage the Contact tti, relay |35 will .be energized which,through its front contact |136, will connect one side of armatures |42and |43 to ground, The opposite side oi the armatures will remainconnected to the positive terminal of source |23 through back contact|45 of relay i3?. Relay |38 will be energized at the same time toconnect fields it@ and |49 across the circuit. Motors I9 and i2@ willthereupon operate in synchronism, as previously described-until suchtime as cam ist attains a position where projection 82 'engages slopingsurface 92 or 93. At such time, indicator 35 will be in coincidence withselector 25. Relays |36 and |38 will thereupon become deenergized. Whenrelay arm |40 engages back contact ii, a direct short-circuit will beplaced across armatures |42 and |43 through relay armatures lll and Mil.As relay |38 is a slow release relay, its armature ld will remain inengagement with front contact |5| for a small interval of time, thuskeeping motor elds |48 and Ell@ energized. The result is that the motorsI9 and |26 act as generators feeding into a shortcircuit. This willcause substantially instantaneous stopping of the armatures M2 and |43by dynamic braking. Subsequent to the time of such stopping, relayarmature |50 will drop, opening the motor elds and restoring the circuitto the positions shown in Fig. 9. The stopping has to be substantiallyinstantaneous, as otherwise switch 32 would 'be closed in the oppositedirec tion to cause reverse movement of the motors. Such reversemovement would not, however, destroy the eicacy of the system, as itwould simply mean that cam 33 would be restored to a poition wherein theprojection 32 engages one of its sloping surfaces 92 or S3 restoringswitch 32 to its neutral position. rIhus indicator 35 and cam 33 aredriven in synchronous relation with member |l'5 and actuator |22.

A further feature of the invention is the provision of a projection |55(Figs. 1, 2 and 3) on the indicator 35. The pilot can tell merely byfeeling the projection |55 and the point |56 of selector when the twoelements coincide and thereby ascertain that member H5 has attained itspreselected actuated position. This feature is useful in the event it isnecessary to operate the device under conditions where no light isavailable or visual perception not feasible.

Although a specific embodiment has been shown and described for thepurpose of illustrating the application of the principles thereof, it

9A willbe understood that the invention may be otherwise embodiedwithout departing from such principles.

What is claimed is:

1. A position preselecting and indicating unit comprising, incombination, a housing; said housing4 having a tubular extension; ashaft extending throughsaid extension; a sleeve rotatably mounted onsaid shaft; a switch mounting plate in rsaid housing secured to theinner end of said sleeve; a `cani in said housing. secured to the innerend of said shaft; a position selector mounted on said housing; meanssecuring said selector against rotation relative to said sleeve; aposition indicator; means securing said positionA indicator to the outerend of said shaft; a cup-shaped knob rotatably mounted on said shaft;aclutch device rotatably mounted on said shaft within said knob;releasable means normally connecting said knob and clutch device formovement as a unit; reduction gearing mounted in said knob andoperatively connecting saidy clutch device to said position selector andsaid switch mounting plate; switch means on said switch mounting plateoperatively associated with said cani selectively operable bydisplacement of said cam from a neutral position; an electric-motormounted on said housing; gearing operatively connecting said motor tosaid cam; and circuit connections between said switch means and saidmotor.

2. A position preselecting and indicating unit comprising, incombination, a housing; said housing having a tubular extension; a shaitextending through said extension; a sleeve rotatably mounted cn-saidshaft; a switch mounting plate in said housing secured to the inner endof said sleeve; a cam in said housing secured to the inner end of saidshaft; a position selector mounted on said housing; means securing saidselector against rotation relative to said sleeve; a position indicator;means securing said position indicator to the outer end ci said shaft; acup shaped knob rotatably mounted on said shaft; a clutch devicerotatably mounted on said shaft within said knob; releasable meansnormally' connecting said knob and clutch device for movement as a unit;reduction gearing mounted in said knob and operatively connecting saidclutch device to said position'selector and said switch mounting plate;switch means on said switch mounting plate operatively associated withsaid cam; an electric motor mounted on said housing; operativelyconnecting said motor to said cam selectively operable by displacementof said cam from a neutral position; and circuit connections betweensaid switch meansand said motor; said position selector and saidposition indicator each being formed with a vprotiiberance whereby therelative positions thereof may be determined by the sense of touch of anoperator.

A position preselecting and indicating mechanism comprising, incombination, a housing, said housing having a tubular extension with asplined outer end; a iirst gear having a hub portion extending throughsaid extension into said housing, the inner end of said hub portionbeing splined; a cam rotatably mounted in said housing; a shaft securedto said cam and extending outwardly through and beyond said hub portion;a position indicator secured to the outer end of said shaft; a cupshaped knob rotatably mounted on said shaft; a splined sleeve rotatableon said tubular extension; a position selector mounted on said housing;a switch mounting plate rotatabiymounted in said housing, said switchmounting plate being fixed to the inner end of said gear hub portion; asecond gear fixed on the splined outer end oi said tubue lar housingextension; a third gear fixed on the enter end oi said splined sleeve;said second being mounted between said first gear and said third gear;aid position selector being fixed to the inner end of said splinedsleeve and being mounted between said third gear and said housaclutch'device rotatably mounted on said "tv witl n said knob; releasablemeans nor'- cf :ing (l knob and clutch device fit as a unit; pinionsmounted for rotation as a unit on said clutch device, each of g andbeing revolvable about witch 4means on said switch I ting plate operativv r'associated with'said cam, switch means being closed upon move'- n tof said plate from a neutral position rela'- e to i; secon-:i gearhaving a ieter diiering rom that of the other two whereby revolution ofsaid pinions about aid gears will cause movement of said irst and iirdgears relative to said second gear to move aid position selector andsaid switch mounting L ate relative to saidcarn; and driving meanseffective, upon closure of said switch means,` to move said indicatorinto coincidence with said selector and tomov'e saidcam into a neutralposition relative to said mounting plate to open said switch means.

4. A position preselecting and indicating mechll anismcornprising, incombination, a housing, said housing ha ing a tubular extension with asplined outer end; a first gear having a hub portion exi tending throughsaid extension into said housing, the inner end of said hub portionbeing fed; a cam rotatably mounted in said houssh'aft secured to saidcam and extending outwardly through and beyond said gear hub por'- tion;a position indicator secured to the outer end of said shaft; a cupshaped knob rotatably mounted` on shaft; a splined sleeve rotatable onsaid tubular extension; a position selector mountedon said nous i. aswitch mounting plate rotatably mounted in said' housing, said switchnio `ntng plate being fixed to the inner end of said gear hub portion; asecond gear fixed on the splined outer end of said tubular housingextension; a third gear on the outer end of said splicedV sleeve; saidsecond gear being mounted between rst gear and said third gear; saidposition selector being iixed to the inner end of said splined sleeveand being mounted between said third gear and said housing; a clutchdevice rotatably mounted onsaid shaft within said knob; releas blemeans-normally connecting said knob and'clu chl device for movement as aunit; pinio'n's' mountedfor rotation as aunit on saidclutch device, eachof said pinions engaging and being revolvable about one of said gears;switch means on said switch mounting plate operatively associated withsaid cam, said switch means being closed upon movement of said platefrom a neutral position relative to said cam; said second gear having adiameter diering from that of the other two gears whereby revolution ofsaid pinions about gears will cause movement of said first and thirdgears relative to said second gear to :nove position selector and saidswitch mounting plate relative to said cam; an electric motor mountedsaid housing; gearing operatively connecting said motor to said cam; andcirm ce 1 1 cuit connections between said switch means and said motor.

5. A position preselecting and indicating unit comprising, incombination, a housing; said housing having a tubular extension; a shaftextending through said extension; a sleeve rotatably mounted on saidshaft; a switch mounting plate in said housing secured to the inner endof said sleeve; a cam in said housing secured to the inner end of saidshaft; a position selector mounted on said housing; means securing saidselector against rotation relative to said sleeve; a position indicator;means securing said position indicator to the outer end of said shaft; acup shaped knob rotatably mounted on said shaft; a clutch devicerotatably mounted on said shaft within said knob; releasable meansnormally connecting said knob and clutch device for movement as a unit;reductionv gearing mounted in said knob and operatively connecting saidclutch device to said position selector and said switch mounting plate;switch means on said switch mounting plate operatively associated withsaid cam selectively operable by displacement of said cam from a neutralposition and adapted to selectively control a positioning motor for amovable member; and means operable in concordance with the movablemember to move said cam to a neutral position relative to said switchmeans,

6. A position preselecting and indicating unit comprising, incombination, a housing; said housing having a tubular extension; a shaftextending through said extension; a sleeve rotatably mounted on saidshaft; a switch mounting plate in said housing secured to the inner endof said sleeve; a cam in said housing secured to the inner end of saidshaft; a position selector mounted on said housing; means securing saidposition indicator to the outer end of said shaft; a cup shaped knobrotatably mounted on said shaft; a clutch device rotatably mounted onsaid shaft within said knob; releasable means normally connecting saidknob and clutch device for movement as a unit; reduction gearing mountedin said knob and operatively connecting said clutch device to saidposition selector and said switch mounting plate; switch means on saidswitch mounting plate operatively associated with said cam selectivelyoperable by displacement of said cam from a neutral position and adaptedto selectively control a positioning motor for a movable member; andmeans operable in concordance with the movable member to move said camto a neutral position relative to said switch means; said positionselector and said position indicator each being formed with aprotuberance whereby the relative positions thereof may be determined bythe sense of touch of an operator.

7. A position preselecting and indicating mechanism comprising, incombination, a housing,

said housing having a tubular extension with a splined outer end; a rstgear having a hub portion extending through said extension into saidhousing, the inner end of said hub portion being splined; a camrotatably mounted in said housing; a shaft secured to said cam andextending outwardly through and beyond said gear hub portion; a positionindicator secured to the outer end of said shaft; a cup shaped knobrotatably mounted on said shaft; a splined sleeve rotatable on saidtubular extension; a position selector mounted on said housing; a switchmounting plate rotatably mounted in said housing, said switch mountingplate being Xed to the inner end of said gear hub portion; a second gearXed on the splined outer end of said tubular housing extension; a thirdgear ilxed on the outer end of said splined sleeve; said second gearbeing mounted between said first gear and said third gear; said positionselector being ixed to the inner end of said splined sleeve and beingmounted between said third gear and said housing; a clutch devicerotatably mounted on said shaft within said knob; releasable meansnormally connecting said knob and clutch device for movement as a unit;pinions mounted for rotation as a unit on said clutch device, each ofsaid pinions engaging and being revolvable about one of said gears;switch means on said switch mounting plate operatively associated withsaid cam, said switch means being closed upon movement of said platefrom a neutral position relative to said cam to selectively control apositioning motor for a movable member; said second gear having adiameter diifering from that of the -other two gears whereby revolutionof said pinions about said gears will cause movement of said first andthird gears relative to said second gear to move said position selectorand said switch mounting plate relative to said cam; and means operablein concordance with the movable member to move said cam to a neutralposition relative to said switch means. WILLIAM P. LEAE.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 932,031 Krone et al Aug. 24, 19991,559,525 Murphy et al Oct. 27, 1925 1,731,776 Henry Oct. 15, 19291,954,142 Moffett Apr. 10, 1934 2,095,208 Wilhelm et al Oct. 5, 19372,147,674 Satterlee Feb. 21, 1937 2,294,210 Roters Aug. 25, 19422,342,717 Yardeny Feb. 29, 1944 2,851,451 Obszarny June 13, 1944

